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Robotics and the Common Sense Informatic SituationMurray Shanahan1Abstract. This paper proposes a logic-based framework in which arobot constructs a model of the world through an abductive processwhereby sensor data is explained by hypothesising the existence,locations, and shapes of objects. Symbols appearing in the resultingexplanations acquire meaning through the theory, and yet aregrounded by the robotÕs interaction with the world. The proposedframework draws on existing logic-based formalisms forrepresenting action, continuous change, space, and shape.INTRODUCTIONWithout ignoring the lessons of the past, the nascent area ofCognitive Robotics [Lesprance, et al., 1994] seeks to reinstate theideals of the Shakey project, namely the construction of robotswhose architecture is based on the idea of representing the world bysentences of formal logic and reasoning about it by manipulatingthose sentences. The chief benefits of this approach are,¥ that it facilitates the endowment of a robot with the capacityto perform high-level reasoning tasks, such as planning, and¥ that it makes it possible to formally account for the success(or otherwise) of a robot by appealing to the notions ofcorrect reasoning and correct representation.This paper concerns the representation of knowledge about theobjects in a robotÕs environment, and how such knowledge isacquired. The main feature of this knowledge is its incompletenessand uncertainty, placing the robot in what McCarthy calls thecommon sense informatic situation [1989]. The treatment given inthe paper is rigorously logical, but has been carried through toimplementation on a real robot.1 ASSIMILATING SENSOR DATAThe key idea of this paper is to consider the process of assimilatinga stream of sensor data as abduction. Given such a stream, theabductive task is to hypothesise the existence, shapes, and locationsof objects which, given the output the robot has supplied to itsmotors, would explain that sensor data. This is, in essence, the mapbuilding task for a mobile robot.More precisely, if a stream of sensor data is represented as theconjunction  of a set of observation sentences, the task is to findan explanation of  in the form of a logical description (a map) Mof the initial locations and shapes of a number of objects, such that,B E N M